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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,261 @@ | ||
| #include "communication.h" | ||
| #include "networkgraph.h" | ||
| #include <sys/socket.h> | ||
| #include <pthread.h> | ||
| #include <netinet/in.h> | ||
| #include <memory.h> | ||
| #include <stdio.h> | ||
| #include <stdlib.h> | ||
| #include <errno.h> | ||
| #include <netdb.h> | ||
| #include <unistd.h> | ||
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| static int _send_packet_out(int socket_file_descriptor, char *packet_data, unsigned int packet_size, unsigned int destignation_udp_port_number) | ||
| { | ||
| // Sends the packet to the specified IP and port. | ||
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| int r_bytes; | ||
| struct sockaddr_in destignation_address; | ||
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| struct hostent *host = (struct hostent *) gethostbyname("127.0.0.1"); | ||
| // Search the host by the name 127.0.0.1 | ||
| destignation_address.sin_family = AF_INET; | ||
| destignation_address.sin_port = destignation_udp_port_number; | ||
| destignation_address.sin_addr = *((struct in_addr *)host->h_addr); | ||
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| r_bytes = sendto(socket_file_descriptor, packet_data, packet_size, 0, (struct sockaddr *)&destignation_address, sizeof(struct sockaddr)); | ||
| // Sends the packet using sendto system API and returns the number of bytes sent. | ||
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| return r_bytes; | ||
| } | ||
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| static unsigned int udp_port_number = 40000; | ||
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| static unsigned int get_next_udp_port_number() | ||
| { | ||
| // Returns a unique udp port number. | ||
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| return udp_port_number++; | ||
| } | ||
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| void initialize_udp_port_socket(network_node_t *network_node) | ||
| { | ||
| // Initializes the udp port socket for the network node. | ||
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| network_node->udp_port_number = get_next_udp_port_number(); | ||
| // Fetches a unique UDP port number. | ||
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| int udp_socket_file_descriptor = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); | ||
| // Creating a unique UDP Socket. | ||
| // | ||
| // AF_INET is an address family that is used to designate the type of addresses that | ||
| // socket can communicate with (in this case, Internet Protocol v4 addresses) | ||
| // | ||
| // SOCK_DGRAM is a datagram-based protocol. | ||
| // We send one datagram and get one reply and then the connection terminates. | ||
| // | ||
| // IPPROTO_UDP defined the protocols to be used for the UDP programming. | ||
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| struct sockaddr_in node_address; | ||
| // The SOCKADDR_IN structure specifies a transport address and port for the AF_INET address family. | ||
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| node_address.sin_family = AF_INET; | ||
| node_address.sin_port = network_node->udp_port_number; | ||
| node_address.sin_addr.s_addr = INADDR_ANY; | ||
| // INADDR_ANY is used when we don't need to bind a socket to a specific IP. | ||
| // When we use this value as the address when calling bind(), | ||
| // the socket accepts connections to all the IPs of the machine. | ||
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| if(bind(udp_socket_file_descriptor, (struct sockaddr *)&node_address, sizeof(struct sockaddr)) == -1) | ||
| { | ||
| printf("ERROR: Socket binding failed for the network node %s\n", network_node->network_node_name); | ||
| return; | ||
| } | ||
| // bind function binds the socket to the address and port number specified in addr. | ||
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| network_node->udp_socket_file_descriptor = udp_socket_file_descriptor; | ||
| // Assigns the created UDP file descriptor. | ||
| } | ||
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| static char recieved_buffer[MAXIMUM_PACKET_BUFFER_SIZE]; | ||
| static char send_buffer[MAXIMUM_PACKET_BUFFER_SIZE]; | ||
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| static void _packet_recieve(network_node_t *recieving_node, char *packet_with_aux_data, unsigned int packet_size) | ||
| { | ||
| // Used to segrigate header and the payload in the packet recieved. | ||
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| char *recieving_interface_name = packet_with_aux_data; | ||
| network_interface_t *recieving_interface = get_network_node_interface_by_name(recieving_node, recieving_interface_name); | ||
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| if(!recieving_interface) | ||
| { | ||
| printf("ERROR : Packet recieved on unknown network interface %s on network node %s\n", recieving_interface->interface_name, recieving_node->network_node_name); | ||
| return; | ||
| } | ||
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| packet_recieve(recieving_node, recieving_interface, packet_with_aux_data + NETWORK_INTERFACE_NAME_SIZE, packet_size - NETWORK_INTERFACE_NAME_SIZE); | ||
| // Third argument is the actual data. | ||
| } | ||
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| static void * _network_start_packet_reciever_thread(void *argument) | ||
| { | ||
| // The defined function will be executed by thread. | ||
| // Based on destignation port number, number in the echoed data recieved by our application, | ||
| // application hand over the data to destignation node. | ||
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| network_node_t *network_node; | ||
| doublylinkedlist_t *current; | ||
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| fd_set active_socket_file_descriptor, backup_socket_file_descriptor; | ||
| // Defining variables to store udp socket file descriptors. | ||
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| int socket_max_file_descriptor = 0; | ||
| int bytes_recieved = 0; | ||
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| network_graph_t *topology = (void *)argument; | ||
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| int address_length = sizeof(struct sockaddr); | ||
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| FD_ZERO(&active_socket_file_descriptor); | ||
| FD_ZERO(&backup_socket_file_descriptor); | ||
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| struct sockaddr_in sender_Address; | ||
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| ITERATE_DOUBLY_LINKED_LIST_BEGINING(&topology->network_node_list, current) | ||
| { | ||
| network_node = graph_glue_to_node(current); | ||
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| if(!network_node->udp_socket_file_descriptor) | ||
| { | ||
| continue; | ||
| } | ||
| // Skips the node for which the file descriptor is not defined. | ||
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| if(network_node->udp_socket_file_descriptor > socket_max_file_descriptor) | ||
| { | ||
| socket_max_file_descriptor = network_node->udp_socket_file_descriptor; | ||
| } | ||
| // Assigns the maximum file descriptor to another variable. | ||
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| FD_SET(network_node->udp_socket_file_descriptor, &backup_socket_file_descriptor); | ||
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| } ITERATE_DOUBLY_LINKED_LIST_END(&topology->network_node_list, current) | ||
| // Iterating over each node of the topology and add add each udp file descriptor of each node | ||
| // to the backup file descriptor in orfer to monitor them. | ||
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| while(1) | ||
| { | ||
| // We need to listen for infinite time as the user can recieve the packet anytime. | ||
| memcpy(&active_socket_file_descriptor, &backup_socket_file_descriptor, sizeof(fd_set)); | ||
| // Copying all the backup file descriptor to active. | ||
| select(socket_max_file_descriptor+1, &active_socket_file_descriptor, NULL, NULL, NULL); | ||
| // Select is a blocking system call. | ||
| // For all the present file descriptor, unless one is activated the system call will | ||
| // remain blocked. | ||
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| // When the data is recieved we need to iterate over all of the data and process it. | ||
| ITERATE_DOUBLY_LINKED_LIST_BEGINING(&topology->network_node_list, current) | ||
| { | ||
| network_node = graph_glue_to_node(current); | ||
| // We will fetch a particular node from the graph. | ||
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| if(FD_ISSET(network_node->udp_socket_file_descriptor, &active_socket_file_descriptor)) | ||
| { | ||
| // Cecking if the file descriptor of the current node is active or not. | ||
| // If activated, we need to recieve the data on the specified node. | ||
| memset(recieved_buffer, 0, MAXIMUM_PACKET_BUFFER_SIZE); | ||
| bytes_recieved = recvfrom(network_node->udp_socket_file_descriptor, (char *)recieved_buffer, MAXIMUM_PACKET_BUFFER_SIZE, 0, (struct sockaddr *)&sender_Address, &address_length); | ||
| // Recieving the data from recvfrom API. | ||
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| _packet_recieve(network_node, recieved_buffer, bytes_recieved); | ||
| // Processing the recieved packet. | ||
| } | ||
| } ITERATE_DOUBLY_LINKED_LIST_END(&topology->network_node_list, current) | ||
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| } | ||
| } | ||
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| void network_start_packet_reciever_thread(network_graph_t *network_topology) | ||
| { | ||
| // We will do this process using threads as we are required to listen to all the nodes | ||
| // of the network simultaneously. (Multithreading) | ||
| // | ||
| // pthread library is being used for multithreading support. | ||
| pthread_attr_t attribute; | ||
| pthread_t recieve_packet_thread; | ||
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| pthread_attr_init(&attribute); | ||
| // Initialising pthread attribute. | ||
| pthread_attr_setdetachstate(&attribute, PTHREAD_CREATE_DETACHED); | ||
| // When a thread is created detached (PTHREAD_CREATE_DETACHED), its thread ID and | ||
| // other resources can be reused as soon as the thread terminates. | ||
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| pthread_create(&recieve_packet_thread, &attribute, _network_start_packet_reciever_thread, (void *)network_topology); | ||
| // Creates a thread and uses the followinf function on thread creation. | ||
| } | ||
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| int send_packet_out(char *packet, unsigned int packet_size, network_interface_t *network_interface) | ||
| { | ||
| // Node communicates by sending data to Node's port number with IP=127.0.0.1 | ||
| int r_bytes=0; | ||
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| network_node_t *sending_node = network_interface->attached_node; | ||
| network_node_t *neighbour_node = get_neighbour_node(network_interface); | ||
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| if(!neighbour_node) | ||
| { | ||
| // Returns -1 in case no node is found to avoid errors as data can only be transfered | ||
| // between connecting nodes. | ||
| return -1; | ||
| } | ||
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| unsigned int destignation_udp_port_number = neighbour_node->udp_port_number; | ||
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| int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); | ||
| // Creating a network udp socket. | ||
|
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| if(sock < 0) | ||
| { | ||
| printf("ERROR : Sending Socket Creation failed, errorno = %d", errno); | ||
| return -1; | ||
| } | ||
|
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| network_interface_t *other_interface = &network_interface->attached_link->interface1== \ | ||
| network_interface?&network_interface->attached_link->interface2:&network_interface->attached_link->interface1; | ||
| // Checking which interface to send data to by checking the connected interface. | ||
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| memset(send_buffer, 0, MAXIMUM_PACKET_BUFFER_SIZE); | ||
| // Clears the memory (removes garbage) from the send_buffer | ||
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| char *packet_with_auxilarry_data = send_buffer; | ||
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| strncpy(packet_with_auxilarry_data, other_interface->interface_name, NETWORK_INTERFACE_NAME_SIZE); | ||
| // Assigns header to the packet. | ||
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| packet_with_auxilarry_data[NETWORK_INTERFACE_NAME_SIZE] = '\0'; | ||
| // Terminates the packet header. | ||
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| memcpy(packet_with_auxilarry_data + NETWORK_INTERFACE_NAME_SIZE, packet, packet_size); | ||
| // Assigns data to the packet. | ||
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| r_bytes = _send_packet_out(sock, packet_with_auxilarry_data, packet_size + NETWORK_INTERFACE_NAME_SIZE, destignation_udp_port_number); | ||
| // Send the packet to the destignation. | ||
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| close(sock); | ||
| // Closes the socket created. | ||
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| return r_bytes; | ||
| } | ||
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| int packet_recieve(network_node_t *network_node, network_interface_t *network_interface, char *packet, unsigned int packet_size) | ||
| { | ||
| // Entry point into data link layer from physical layer | ||
| // Represent the start of ingress journey of the packet start from here in TCP/IP Stack | ||
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| printf("Message Recieved : %s, on node : %s, IIF: %s\n", packet, network_node->network_node_name, network_interface->interface_name); | ||
|
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| return 0; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| #ifndef __COMMUNICATION__ | ||
| #define __COMMUNICATION__ | ||
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| #define MAXIMUM_PACKET_BUFFER_SIZE 2048 | ||
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| typedef struct network_node_ network_node_t; | ||
| typedef struct network_interface_ network_interface_t; | ||
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| int send_packet_out(char *packet, unsigned int packet_size, network_interface_t *network_interface); | ||
| // Defining API to send the network packet out of the interface. | ||
| // Accepting the packet is dependent on reciever end. | ||
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| int packet_recieve(network_node_t *network_node, network_interface_t *network_interface, char *packet, unsigned int packet_size); | ||
| // Defining API used to recieve packet from the reciever. | ||
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| #endif |
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